1. Field of the Invention
The present invention relates generally to chain saws and more specifically to a chain saw automatic tensioner, which keeps a cutting chain of a chain saw tensioned during use.
2. Discussion of the Prior Art
The prior art includes at least three patents that disclose chain saw tensioners. U.S. Pat. No. 5,709,254 to Argue discloses a tree harvesting apparatus. The Argue patent includes a chain saw chain detensioning system, which permits a quick removal of a saw chain from the chain saw without the use of tools. U.S. Pat. No. 6,032,373 to Peterson discloses methods and apparatus for adjusting chain saw tension. The Peterson patent includes a first piston operable to move the support bar radially away from the drive sprocket and a second piston is operable to limit such movement. U.S. Pat. No. 6,539,832 to Nilsson discloses a hydraulic stretching device for a chain saw. The Nilsson patent includes a hydraulic stretching device for a saw chain active in a sawing apparatus.
Accordingly, there is a clearly felt need in the art for a chain saw automatic tensioner, which keeps a cutting chain of a chain saw tensioned during use and has the unexpected result of protecting a cutting chain from flying off a chain sprocket.